Solution:

54
x3
===
162

Solution:

There are 5 Insect-A, 7 Insect-B & 6 Insect-C.

Let 'A' be the number of Insect-A, 'B' be number of Insect-B and 'C' be number of Insect-C.
A+B+C = 18
8A+6B+6C = 118
2B+C = 20
Solving this, A=5, B=7, C=6

Solution:

24 13 11 5
----------
24 0 0 0
11 13 0 0
6 13 0 5
6 2 11 5
8 0 11 5
8 5 11 0
8 13 3 0
8 8 3 5
8 8 8 0

Solution:

42857

Let the number be x
10x +1 = 3(100,000 + x)
=> x = 42857.

Solution:

720

(0!+0!+0!+0!+0!+0!)!
=(1+1+1+1+1+1)!
=(5)!
=6! is 6*5*4*3*2*1=720

Solution:

4100

some people might guess 5000

Solution:

Little Johny have Rupees 99.98 in his wallet when he entered the store.

Solution:

I am 72 years old.

Let m be my age in years. If s is my son's age in years, then my son is 52s weeks old. If g is my grandson's age in years, then my grandson is 365g days old. Thus,
365g = 52s.
Since my grandson is 12g months old,
12g = m.
Since my grandson, my son and I together are 120 years,
g + s + m = 120.
The above system of 3 equations in 3 unknowns (g, s and m) can be solved as follows.
m / 12 + 365 m / (52 x 12) + m = 120 or
52 m + 365 m + 624 m = 624 x 120 or
m = 624 x 120 / 1041 = 72.
So, I am 72 years old.

Solution:

1

As stated
1=6 => 6=1

Solution:

Didn't you say that you sold your well to this farmer?' Birbal asked the neighbour. 'So, the well belongs to him now, but you have kept your water in his well. Is that right? Well, in that case you will have to pay him a rent or take your water out at once.'The neighbour realized that he was outwitted. He quickly apologized and gave up his claim."